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News: After a season-long heatwave from March to May, the north-northwest and central India are undergoing a rainfall deficit, while Northeast India and Bangladesh are hit with devastating floods.
For instance, Meghalaya’s Mawsynram – the world’s wettest place – recorded more than 1,000 mm of rain for the first time on June 17.
What are the characteristics of ongoing floods?
The winds over the Bay of Bengal have been exceptionally strong for a week. These strong winds carry a lot of moisture, dumping them as rains over Bangladesh and Northeast India.
The ongoing La Nina conditions in the Pacific, in combination with a negative Indian Ocean Dipole (IOD) in the Indian Ocean, has increased the intensity of the floods. This is because this condition strengthens the winds that blow from the southwest to the northeast (Southwesterlies) in the Bay of Bengal.
Note: Negative IOD happens when the Indian Ocean is cool in the west and warm in the east.
What is the reason for changing the monsoon pattern?
Monsoon patterns have seen a climatic shift over South Asia since the 1950s. This is because,
a) The strong monsoon winds in the Bay of Bengal now carry a lot more moisture than ever and result in heavy rains. The moisture-holding capacity of the air has increased with global warming. b) Instead of having moderate rains spread out through the monsoon season, India now has long dry periods interspersed with short spells of heavy rains. For example, a month’s rain is pouring in a day or two now.
For these reasons, both droughts and floods occur across South Asia, and sometimes in the same season. This puts tremendous pressure on the water and food security in the region.
What will be the impact of a 1˚C rise in global temperature for South Asia?
The total amount of rainfall is expected to increase by 7-10% for every 1˚C rise in temperatures. The extreme rainfall events are also projected to increase proportionally over South Asia.
South Asia is the most vulnerable to climate change due to its proximity to the rapidly warming Indian Ocean on its south and the rapidly melting glaciers on its north.
The east coast of India and Bangladesh are particularly vulnerable since the sea-level rise in the North Bay of Bengal region is faster than in other regions due to a gradually sinking land. Also, storm surges are particularly large in the Bay of Bengal as compared to the Arabian Sea.
The combined effect of sea-level rise and storm surges leads to the saltwater intrusion that affects agriculture and cholera epidemics on the east coast of India and Bangladesh.
What should be done?
a) The countries need to disaster-proof every district and village of South Asia and make them climate-resilient, b) Make houses and farms for both droughts and floods, c) Policies should be framed so that they help to redesign cities and prepare rural areas for intensifying cyclones, floods and heatwaves.
Source: This post is based on the article “Why North Is Rain-Starved & Northeast Is Flooded” published in The Times of India on 21st June 22.
